I've seen savvy commentary that we may just be stealing from next year's stock market returns.
IIRC, someone said that cash on the sidelines peaked at 50% earlier in the year, and is now 30% (historical average is 20%)?
Money managers that are lagging their benchmarks and at risk of losing assets under management will scramble to lock in whatever trading gains they can get to hopefully close gap by year end (or maybe not be in business next year).
Plus, I think third and fourth quarter comps will be very easy to beat because of how the economy just fell off a clip last fall. Companies had no visibility going forward and apparently cut inventory and jobs over-aggressively (retro-spectively).
One experienced money manager, Longleaf Partners, seems to think major risks to their conservative assessments are 1) crashing of U. S. dollar, and 2) out of control inflation.
Whether either of those could take out the lows of earlier this year (SP500 666)... I don't know, but kind of doubt it.